The nitrogenous bases are the building blocks of DNA and RNA, playing a crucial role in the storage and transmission of genetic information. These bases are categorized into two types: purines and pyrimidines.
DNA Nitrogenous Bases
DNA contains four nitrogenous bases:
- Adenine (A): A purine base that pairs with Thymine in DNA.
- Thymine (T): A pyrimidine base that pairs with Adenine in DNA.
- Cytosine (C): A pyrimidine base that pairs with Guanine in DNA.
- Guanine (G): A purine base that pairs with Cytosine in DNA.
RNA Nitrogenous Bases
RNA also contains four nitrogenous bases, but with one key difference:
- Adenine (A): A purine base that pairs with Uracil in RNA.
- Uracil (U): A pyrimidine base that replaces Thymine and pairs with Adenine in RNA.
- Cytosine (C): A pyrimidine base that pairs with Guanine in RNA.
- Guanine (G): A purine base that pairs with Cytosine in RNA.
These bases form specific pairs (A-T and C-G in DNA; A-U and C-G in RNA) through hydrogen bonding, creating the double-helix structure of DNA and the single-stranded structure of RNA. This pairing is essential for the replication and transcription processes, ensuring the accurate transfer of genetic information.